Geminids to Shower Meteor 'Gems' on Skywatchers Next Week

The Geminid meteor shower, on the morning of Tuesday, Dec. 14, is the best for 2010. This view shows the radiant at its highest point, at 1 a.m. ET on Dec. 14. Bright stars and constellations are shown as landmarks.Credit: Starry Night Software [Full Story]

November's
Leonid meteor shower may have passed us by, but that doesn?t mean there
aren't any
good meteor displays to look forward to as the end of 2010 draws near.
In fact,
one of the best is just around the corner, scheduled to reach its peak
next
week: the Geminid meteor shower.

The
Geminids
get their name from the constellation of Gemini, the Twins, where the
display
of so-called "shooting stars" appears to originate from the night
sky. During the overnight hours of Dec. 13 and Dec. 14, the
night of this
shower?s peak, the meteors should appear to emanate from a spot in the
sky near
the bright star Castor in Gemini.

This
sky map shows where to look for the Geminid meteor shower
when it peaks on
Dec. 13 and Dec. 14.

December's
meteor gems

The
Geminid meteors are ? for those willing to brave the chill of a
December night ?
a fine winter shower, and usually the most satisfying of all the annual
showers.
They can even surpass the famous Perseid meteors of August at their
peak.

Studies
of past displays show that this shower has a reputation for being rich
in slow,
bright, graceful meteors and fireballs as well as faint meteors, with
relatively fewer objects of medium brightness. Many appear
yellowish in hue.
Some even seem to form jagged or divided
paths.

According
to the late meteor specialist Neil Bone, at 2 grams per cubic
centimeter (0.07
pounds per cubic inch) on average, Geminid meteoroids are several times
denser
than the cometary dust flakes that supply most meteor showers. Add this
to the
relatively slow speed with which Geminids typically encounter Earth ?
about 22
miles (35 km) per second ? about half the speed of a Leonid
meteor, and you have a recipe for meteors that linger a bit
longer in view than
most.

The
Earth moves quickly through this meteor stream. The rate of
meteors increases
steadily for two or three days before maximum, reaching roughly above a
quarter
of its peak strength, then drops off sharply, lasting for
only about a day
afterward.

Those
late Geminids, however, tend to be especially bright. A few renegade
forerunners and late stragglers might be seen for a week or more before
and
after the peak night. One interesting finding made recently from video
analysis
by the International Meteor Organization was that Geminids have been
detected
as early as Nov. 30 ? totally unexpected from past visual
observations.

Some lunar
Interference

The
Geminids usually perform splendidly every year, although as was the
case for
last month?s Leonids, the moon is going to pose a bit of a problem this
time.
In fact, the moon will reach first quarter phase on Dec. 13, the same
night as
the Geminid
peak, shining brightly in the dim constellation of Pisces,
the Fishes. That
means that many of the fainter Geminid streaks will likely be washed
out by the
bright moonlight.

But
unlike the Leonids, where the moon was brightly illuminating the sky
most of
the night, in the case of the Geminids the moon will be setting around
12:30
a.m. (your local time) early on Tuesday, Dec. 14. That means
that the sky will
be dark and moonless for the balance of the night, making for perfect
viewing
conditions for the shower.

Perfect timing!

In
addition, according to Margaret Campbell-Brown and Peter Brown in the
2010
Observer?s Handbook of the Royal Astronomical Society of Canada, peak
activity
is projected to occur at or near 6 a.m. EST on Dec. 14.

Under
normal conditions on the night of maximum activity, with ideal dark-sky
conditions, at least 60 to 120 Geminid meteors can be expected to burst
across
the sky every hour on average (light pollution greatly cuts these
numbers). So,
in 2010, along with a lack of significant moonlight, North Americans
are
projected to be the best situated to catch the very crest of the
shower, when
the hourly rates conceivably could exceed 120!

British
meteor astronomer Alastair McBeath also points out that a new detailed
analysis
confirms that Geminid near-peak activity is very persistent with hourly
rates
of around 80 to 130 often seen for almost a day around the predicted
time of
maximum, corresponding this year from about 1900 UT on Dec. 13 to 1600
UT on
Dec. 14. So from virtually anywhere on Earth, an excellent
Geminid show can be
anticipated.

Bundle up!

A
productive Geminid watch can actually begin as early as 10 p.m. local
time,
because the shower?s radiant (where the meteors appear to originate
from) is
already fairly high in the eastern sky by then. Even with that
annoyingly
bright moon still high in the western sky, it will be worth watching
for some
early "Gems."

But
keep this in mind: At this
time of year, meteor
watching can be a long, cold business. You wait and you wait for
meteors to
appear. When they don't appear right away, and if you're cold and
uncomfortable, you're not going to be looking for meteors for very
long.
Therefore, make sure you're warm and comfortable.

Warm
cocoa or coffee brought along in a thermos can take the edge
off the chill, as well as provide a slight stimulus. It's even better
if you
can observe with friends. That way, you can keep each other awake, as
well as
cover more sky. Give
your eyes time to adapt to the dark before starting.

Debris
from a dead comet?

The
Geminids will be especially noticeable right after the moon sets, as
their
radiant point will be passing nearly overhead. The higher a
shower?s radiant,
the more meteors it produces all over the sky.

The
track of each meteor does not necessarily begin near Castor, or even in
the
constellation Gemini, but it always turns out that the path of a
Geminid
extended backward along the direction of flight passes through a tiny
region of
sky about 0.2 degrees in diameter (an effect of perspective). In
apparent size,
that?s less than half the width of the moon.

As
such, this is a rather sharply defined radiant as meteor showers go,
suggesting
the stream is "young" ? perhaps only several thousand years old.

Geminids
stand apart from the other meteor showers in that they seem to have
been
spawned not by a comet, but by 3200
Phaeton, an Earth-crossing asteroid. Then again, the Geminids
may be comet
debris after all, for some astronomers consider Phaeton to be the dead
nucleus
of a burned-out comet that somehow got trapped into an unusually tight
orbit.